The use of computer generated 3D models of a patient's anatomy is well established. Such 3D models are based on real image data taken from the patient. The 3D models assist surgeons in planning a surgical procedure.
A number of commercially available systems process 3D image data sets of a patient and prepare a 3D model of the organ for the physician to review in advance of surgery. In some systems, virtual markers and regions of interests may be added or superimposed on the 3D model for review and adjustment by the physician. An example of such a planning system with application to the lung is the LungPoint® Planning System manufactured by Broncus Technologies, Inc. (Mountain View, Calif.).
A challenge with certain planning systems is to compensate for rhythmic or tidal motion of the organ arising from, e.g. breathing. An implant or anatomical feature positioned in the lung based on a 3D image of the lung in one state (e.g., full inspiration) may have a different position when the lung is in another state (e.g., full expiration). Failure to compensate for the displacement of the anatomy, implant, or device as the case may be could thwart the procedure and perhaps in some instances result in patient injury should the implant or device damage a vessel, pleural surface, or other sensitive region.
A number of techniques address to varying degrees of effectiveness the above mentioned challenge. For example, the paper entitled “Fast Deformable Registration on the GPU: A CUDA Implementation of Demons” by Pinar Muyan-Ozcelik, 2008 (hereinafter “the Muyan-Ozcelik paper”) describes a deformable registration technique to map CT scans taken during expiration to CT scans taken during inspiration. However, amongst other things, the Muyan-Ozcelik paper does not appear to compensate for posture and position of the patient prior to deforming the CT images. Accordingly, more is required in order to accurately estimate a motion vector field of the magnitude and direction of local motion of a non-rigid organ such as the lung.
A method and system to assist surgeons to plan medical procedures with a wide variety of medical implements in a body organ, that has application to non-rigid organs such as the lung, and that does not suffer the above identified drawbacks is therefore desired.